#define _CRT_SECURE_NO_WARNINGS 1

#include<stdio.h>
#include<math.h>

#define PI 3.1415926
int main(void)
{
	double n = 0.0;
	double v = 0.0;
	scanf("%lf", &n);
	v = 4.0 / 3.0 * PI * pow(n, 3);
	printf("%.3lf", v);
	return 0;
}